Modern medical practice mandates certain monitoring standards for patients, depending on the acuteness of a patient's condition. For example, blood pressure (BP), pulse oximetry, and electrocardiography are standard monitors for most patients, whether in hospitals, outpatient facilities, nursing homes, or even in a significant number of home care situations. Pulse oximetry relies on pulsatile arterial flow to generate a signal, which is analyzed to determine hemoglobin oxygenation. Pulse oximeters are typically finger-mounted, spring loaded devices with wires connected to some type of display. Automated, non-invasive blood pressure determination utilizes the oscillometric method of blood pressure calculation. This technique inflates a blood pressure cuff above vascular occlusion pressure, which causes a cessation of blood flow and consequently prevents the generation of a signal for pulse oximeter analysis. As a result of this monitoring conflict, the BP cuff and the pulse oximeter are almost invariably placed on opposite arms, so that an inflated BP cuff does not interfere with the blood flow used for oxygen saturation monitoring.
The electrocardiograph is also a basic tool of patient monitoring. Cardiac variables such as rate and rhythm are provided through a system of wires and disposable skin electrodes, which transmit the cardiac depolarization voltage waveforms to a display, such as a modified oscilloscope, or printer, or both, where the waveform is displayed to the medical practitioner. Typically, such a visible waveform, whether displayed by an electronic device or printed on paper, is called an ECG tracing.
In prior art ECGs, a system of wires and disposable skin electrodes constitute electrical connections from the patient to a variety of well known signal processing and display devices. The wires are often grouped together into a harness. The wires and electrodes are configured in standardized arrangements known to those of skill in the art. A signal is generated using two active electrodes. A third, inactive electrode ordinarily serves as a ground. Two active electrodes are often referred to as a “lead.” The electrodes have standardized polarities, and they are usually placed at standardized body locations. These standardized locations create standardized leads which are known to those of skill in the art. For example, FIG. 1 depicts a prior art ECG monitoring system with several wires and skin electrodes. A standardized “lead 1” is defined by two active electrodes placed on the right and left arms. The left arm is by convention defined as the positive electrode. A ground electrode is placed on the left chest wall. Each of the disposable electrodes is connected to a separate wire that is connected to a wire hub M. The left arm-right arm configuration—a “lead 1”—results in a generally positive ECG waveform, as the major cardiac depolarization vector travels from right to left and downward. Other, different electrode locations on the body produce additional, well known leads, each with its own associated waveform.
Variations of ECG monitoring systems and methods exist, depending on the amount of patient information the practitioner desires. For example, a twelve lead ECG is considered by many to represent the standard for a complete assessment of cardiac function, because it provides a substantial amount of information for numerous cardiac conditions. The conditions of most patients do not call for such complex and intense monitoring.
The most typical ECG monitoring setup employs a three-electrode, three-wire system that generates an ECG waveform or tracing. This monitoring setup is encountered in the emergency room, preoperative area, operating room, postoperative area, and frequently in the intensive care unit as well. The medical practitioner typically uses this monitoring setup, because he is primarily or exclusively interested in the patient's heart rate and rhythm. If the practitioner's only interest is in the heart's rate and rhythm, additional wires, and electrodes are superfluous. A three electrode system containing two active electrodes and one ground can generate an ECG tracing sufficient to provide the practitioner with the information he deems necessary.
There are many instances when a single lead (i.e., three electrode) ECG tracing or waveform, combined with oxygen saturation level and blood pressure, provides sufficient patient monitoring information. One instance includes what are known as minor procedures. For example, a patient who has undergone an uneventful cataract removal or a colonoscopy is monitored in the recovery room with a BP cuff, pulse oximetry, and a single lead ECG tracing. Under such circumstances, a more complex system of monitoring is unnecessary. It can also be detrimental. Excessive complexity is physically cumbersome, unnecessarily costly, wastes the practitioner's time, and slows treatment of multiple patients or else requires more human resources to do so. Whether the desired ECG is simple or complex, many types of “vital signs” monitors incorporate ECG, pulse oximetry, and automated blood pressure determination and display within a single unit. Most of these monitors include the multiple wires depicted in FIG. 1. In addition, they also include connections (not shown) from pulse oximeters and blood pressure cuffs.
In prior art monitoring devices, the multiplicity of wires is often referred to derogatively as spaghetti, as the wires tangle or often interfere with other medical hardware and the activities of medical personnel who are treating or attending to the patient. This arrangement increases the likelihood of the disposable electrodes being dislodged from the patient's body. All of these problems unnecessarily increase the use and cost of technical and human medical resources. In many instances, reducing spaghetti and its associated problems is desirable as long as pertinent patient data is not sacrificed. Though the time required for any single patient's ECG harness to be attached and detached may seem insignificant, in aggregate, given the tens of millions of such procedures annually and the premium placed on the efficiency of medical personnel, eliminating the time and problems associated with a multiple wire harness would be substantial.
Various prior art devices and techniques reduce clutter and organize the medical environment. For example, Glass, in U.S. Pat. No. 6,536,699, details the problem of wire and cord entanglement and provides a solution for organization. Webb, in U.S. Pat. No. 5,974,708, provides a solution for organizing intravenous lines. Therefore, it is desirable to provide a patient monitoring device and method that provide a continuous ECG tracing without the use of a multiplicity of wires.